histo exam 2 Flashcards
epidermis is made of what type of cells
stratified squamous; may contain keratinocytes
top to bottom layers of epidermis
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
which epidermal layer:
single layer of cuboidal/columnar cells
anchored to basement membrane via hemidesmosomes
attached to other cells via desmosomes
actively reproductive
stratum basale
which epidermal layer:
multiple layers of polygonal cells
attached to other cells via desmosomes
some reproductive activity
stratum spinosum
which epidermal layer:
single to few layers of plump squamous cells
attached to other cells via desmosomes
cytoplasm filled with keratohyaline granules
may be invisible in thin skin
stratum granulosum
which epidermal layer:
few to many layers of squamous cells
attached to other cells via desmosomes
terminally differentiated cells
may be preceded by stratum lucidum in thick skin
high amount in paw pads and elbows
stratum corneum
cell that synthesizes melanin in melanosomes
share melanin with keratinocytes and macrophages via intercellular processes
usually seen in stratum basale
melanocytes
Ag presenting cells in the epidermis
langerhans cells
how are hair and hair follicles usually oritented
diagonal to surface
base of hair with germinal cell matrix
bulb
innermost column of hair
central cuboidal/columnar cells
absent in wool
medulla
layer of hair following medulla
contains flat cells longitudinal to axis
cortex
layer of hair following medulla
scaly squamous cells
pointing upwards
outer cuticle
dermal papilla of hair follicle is (vascular or avascular)?
vascular
part of hair follicle:
from germinal cells
scaly squamous cell cuticle
points downwards
inner root sheath
part of hair follicle:
abuts (connects to) follicular basement membrane
connective tissue sheath
species with single/simple hair follicles
ruminants and horses (vertical in sheep)
pigs (in groups of 3)
species with compound hair follicles
carnivores
where do compound hair follicles union
sebaceous gland opening
sinus hairs
blood filled sinuses in connective tissue sheath
ex. whiskers
tactile hairs
how does avian epidermis differ from mammalian epidermis
thinner
contains stratum germinativum (basal, intermediate, vacuolated layers) and stratum corneum
no gland except uropygial gland
no papillae
what birds do not have a uropygial gland
emus
ostrich
3 main feather types on adult birds
contour
down
filoplume
feather type:
hollow central shaft (very vascularized in young birds)
hollow quill (calamus)
thinner rachis (barbs and barbules w/ hooks)
contour (and wing/tail feathers)
feather type:
contains hook-less barbules
insulate the body
down
feather type:
hair like
no barbules
filoplume
feather papilla gives rise to ___; germinative cells in growing feathers
feather pulp
layers of feather follicle
stratum corneum
stratum germinativum
connective tissue layer
what is absent filoplumes (no movement)
arrector plumae smooth muscle
avian appendage with high vascularized dermis rich in mucin; can be stained with
wattle and comb
stained with alcian blue stain
thick keratinized outer layer of beaks
ramphotheca
what nerve ending do beaks contain
herbst’s corpuscles
keratinized epidermis covering distal end of digit
hoof
inflammation of laminar dermis
laminitis (founder)
types of animals with epidermal scales
reptiles
birds
mammals (pangolin)
types of animals with dermal scales
fish
reptiles
amphibians
*armadillos
modified and thickened stratum corneum (keratin)
can shed corneal layer
epidermal scales
derived from mesenchyme
remnants of dermal skeleton
bony base
cannot be shed
dermal scales
collagenous connective tissue with a loose irregular superficial layer and deeper dense irregular layer; vascularized; contains glands and nerves
dermis
4 types of dermal glands
sebaceous
apocrine
mammary
uropygial
secretion type of sebaceous glands
holocrine
secretion product of sebaceous glands
lipid product - sebum
sebaceous glands open into
lumen of hair follicle
sebaceous gland in eyelid
common benign tumor in older dogs
meibomian gland
secretion type of sweat (sudoriferous) glands
apocrine or merocrine
secretion product of sweat glands
aqueous; glycosaminoglycans, proteoglycans
sweat glands open into
epidermal surface (merocrine)
or lumen of hair follicle (apocrine)
sweat glands are surrounded by
myoepithelium
contains actin and myosin
secretion type of mammary glands
apocrine
secretion product of mammary glands
milk
mammary glands open into
intralobular ducts
mammary glands are surrounded by
myoepithelium
epithelial type of sebaceous glands
stratified cuboidal
epithelial type of sweat glands
simple or bistratified cuboidal
epithelial type of mammary glands
simple cuboidal
large sebaceous gland in birds for preening
uropygial gland
secretion type of uropygial gland
holocrine secretion
secretion product of uropygial gland
oily sebum
epithelial type of uropygial gland
simple tubules or branched alveoli
uropygial gland opens to
primary duct through papilla onto epidermal surface
origin of arrector pili muscle
superficial dermis
insertion of arrector pili muscle
connective tissue sheath of hair follicle
what stain could you use to distinguish an arrector pili muscle from collagen
trichrome stain
receptor for tactile stimuli
associated with tactile nerve endings
sensitive to touch
merkel cells
receptor found in dermis and visceral organs
detect pressure
looks like an onion
pacinian corpuscle
receptor found in dermis of beaks, lower legs
sensory nerve endings with central nerve, fluid filled lamellae surrounded by a capsule
detect pressure
herbst’s corpuscles
subcutis contains
adipose tissue
what stain can identify fat
oil red o
outermost meninges; attached to endosteum of cranium
dura mater; pachymeninx
second meninges
arachnoid mater
inner most meninges; highly vascular; adherent to brain and spinal cord
pia mater
arachnoid + pia mater
leptomeninx; leptomeninges
contains CSF
subarachnoid space
how is the brain divided
forebrain
midbrain
hindbrain
forebrain
2 cerebral hemispheres
diencephalon - thalamus and hypothalamus
connection between two cerebral hemispheres
corpus collosum
3 parts contained in the cerebral cortex
basal nuclei - motor control
hippocampus
amygdala - limbic system
midbrain contains
mesencephalon
hindbrain contains
metencephalon and medulla oblongata of brain stem
white matter contains
myelinated axons and glial cells, blood vessels
where is white matter located
peripheral in spinal cord
central in brain
gray matter contains
neuronal cell bodies, glial cells and axons, blood vessels
where is gray matter located
peripheral in brain
central in spinal cord
functional cells of the nervous system
neurons
“neural glue”
neurons and glial cells
what “living” properties do neurons possess
irritability
conductibility
provide support and myelin sheath to axons in the CNS; can form myelin sheath for several axons at once
oligodendrocytes
neurons are sensitive to
hypoxia
oligodendrocytes can be destroyed by ___ resulting in demyelination
viruses or toxins
functions of microglial cells
immunosurveillance
immunoregulation
reparative (phagocytic) - role in healing
activated microglial cells; swollen after phagocytizing debris
gitter cells
microglial cells are derived from
blood borne monocyte
CNS counterpart to the fibroblast; protoplasmic in the GM; fibrillar in the WM
astrocytes
what stain can be used as a marker for astrocytes
GFAP
function of astrocytes
transport nutrients from parenchyma to neurons
part of blood brain barrier
antigen presentation
BBB is made up of
basement membrane of endothelial cells
feet of astrocytes
tight junctions of endothelial cells
components of the CNS that originate from the ectoderm and are sensitive to hypoxia
neurons
astrocytes
oligodendrocytes
components of the CNS that originate from the mesoderm and are not as sensitive to hypoxia
microglia
vascular endothelium
nissl substance
remnants of ER
cluster of neuron cell bodies in the CNS with a common function
nucleus
how do nuclei communicate with each other
tracts - pathways of large groups of axons
presence of lipofuscin indiactes
oxidative damage to organelles/cell
release of synaptic vesicles
induces depolarization
neurotransmitter released in a stimulatory synapse
acetylcholine
neurotransmitter released in inhibitory synapse
GABA
thermoreceptors sense
heat and cold
meissner’s corpuscle senses
touch
nociceptor senses
pain
pacinian corpuscle senses
pressure
glial cell that covers papillary projections within the lateral, 3rd and 4th ventricles; line the central canal of the spinal cord and produce CSF
ependymal cells
choroid plexus is composed of
capillaries
ependymal cells appear to be cuboidal epithelial but do not have a ___
basement membrane
function of CSF
nourishes CNS tissue; cushions
where can samples of CSF be taken from
atlanto-occipital area
lumbosacral area
CSF has to be reabsorbed to prevent
hydrocephalus
cells in the molecular layer of the cerebellum GM; outer layer
basket cells
cells in the ganglionic layer of the cerebellum GM; single middle layer
purkinje cells
cells in the granular layer of the cerebellum GM; inner layer
granule cells
what additional layer may infants have in the cerebellum GM
internal granular cell layer; located deep to the molecular cell layer
what fibers travel down the dorsal nerve root of the spinal cord
sensory afferent fibers
dorsal root ganglia contains
afferent cell bodies and dendrites that determine sensory input
what fibers travel up the ventral nerve root of the spinal cord
motor efferent fibers
collection of axons/dendrites in PNS; contains endothelial cells, fibroblasts and schwann cells
nerve
collection of neuronal cell bodies in the PNS
ganglia
thin-like extensions of small glial cells that surround neurons within ganglia
satellite cells
function of ganglia
relay stations to transmit nerve impulses
direction of nerve impulse determines
whether ganglion is sensory or autonomic
slides can be fixed with __ to preserve myelin sheath and appear black with EM
osmium
main purpose of cardiovascular system
deliver oxygen and nutrients; remove CO2 and waste products for metabolization
efferent vessels from the heart; transfer blood with nutrients and oxygen to tissues
arteries
afferent vessels into the heart; transport blood with waste and CO2 to lungs
veins
thin connections between arteries and veins
capillaries
simple squamous epithelium
line all cardiovascular organs
arises from the mesoderm
endothelial cells
capillaries are composed of
simple squamous endothelium
basement membrane - no smooth muscle
tight junctions (zona occludens) and terminal bars (zona adherens)
capillaries function as the sites of
gas exchange
nutrient exchange
immune cell exit into interstitium
3 types of capillaries
continuous
fenestrated
sinusoidal
capillary type that lacks pores or openings
site of minimal to no substance exchange
ex. in BBB, blood-testis barrier
continuous
capillary type that has pores <100nm in the wall of endothelial cells usually closed by a diaphragm; sites of high fluid substance exchange
ex. in intestinal villi, ciliary body, choroid plexus, glomeruli
fenestrated
capillary type that is discontinuous; large pores and large spaces between endothelial cells; discontinuous basement membrane; sites of high particle and cell exchange
ex. in spleen, bone marrow, liver
sinusoidal
cells with elongated nucleus and cytoplasmic projections, with their own basal lamina; partially encircle cells in capillaries and venules; capable of contractility and paracrine communication for angiogenesis
pericytes
where are capillary beds abundant
organs with a high metabolic rate
ex. kidney, liver, cardiac and skeletal muscle
proportion of capillaries w/ open lumen depends on
metarterioles’ sphincters
narrowest branches of arterioles surrounded by smooth muscle and branch into capillaries
metartioles
3 layers of the intima
endothelium
subendothelium
internal elastic membrane
cell type of subendothelium
fibroblasts and minimal ECM
cell type of internal elastic membrane
elastic fibers
layers of the media
smooth muscle
connective tissue - fibroblasts, collagen, elastic fibers
layers of the adventitia
connective tissue - fibroblasts, collagen, elastic fibers
arterioles and venules that supply blood to media/adventitial layers
vasa vasorum
structure of arterioles
intima layer has no subendothelial membrane and very thin or absent elastic membrane
median layer has 4-5 smooth muscle layers, no outer elastic membrane
thin adventitial layer
structure of median layer of small-medium caliber arteries
up to 40 smooth muscle layers
elastic layer present - >caliber = >thickness
muscular arteries
small-medium caliber arteries
elastic arteries
large caliber arteries
ex. aorta
elastic arteries have an indistinguishable ___ layer; are mostly made of media
outer elastic
venules participate in
metabolite exchange and inflammtion
structure of intima layer of venules
endothelium only
some pericytes
structure of median layer of venules
few layers of smooth muscle
structure of adventitial (tunica externa) layer of venules
thin collagenous connective tissue
majority of veins are
small-medium caliber
veins have ___; extensions of the intima, mostly elastic covered by endothelium
valves
structure of intimal layer of veins
+/- subendothelial membrane
structure of median layer of veins
few layers of smooth muscle and collagenous fibers
structure of adventitial layer of sm-med. caliber veins
prominent collagenous connective tissue
structure of adventitial layer of large caliber veins
prominent collagenous connective tissue plus smooth muscle fibers (vasa vasorum)
lymphatic vessels are filled with ___ lymph
protein rich
structure of lymphatic capillaries
blind ended vessels
lined by endothelial cells
openings between cells
overlapping edges prevent backflow
structure of lymphatic vessels
endothelium
valves present
minimal smooth m. or connective tissue
where does the R atrium get CO2 rich blood from
the body via cranial and caudal vena cava
where does the R ventricle send CO2 rich blood
lungs via pulmonary arteries
where does the L atrium get O2 rich blood from
lungs via pulmonary veins
where does the L ventricle send O2 rich blood
body via aorta
the mammalian heart has 4 chambers which allows for
complete separation of de/oxygenated blood
- more efficient than in 3 chamber hearts
fibrous tissue sac enclosing the heart
pericardium
extension of the blood vessels’ intima layer; tunica intima of the heart
endocardium
lines all internal surfaces of the heart
endothelium
tissue layers of endocardium
endothelium
subendothelium
subendocardium
structure of subendothelium
dense compact collagenous tissue + elastic fibers
structure of subendocardium
loose collagenous connective tissue
impulse conducting system - purkinje fibers, blood vessels and nerves
thickest tissue layer of the heart
myocardium
why is the myocardium of the L ventricle thicker than the R
more force is required to pump blood to all the body than just to the lungs
wear and tear pigment sometimes seen in cardiac muscle
lipofuscin
outermost tissue layer, visceral capsule of the heart
serosal membrane
epicardium
tissues of the epicardium
mesothelium
subepicardium
structure of mesothelium in epicardium
simple squamous
supported by loose collagenous connective tissue
continuous with inner surface of pericardial sac
structure of subepicardium
loose collagenous connective tissue with nervous ganglia, adipose tissue, blood vessels and nerves
tissue of cardiac valves
dense fibrous connective tissue covered with endothelium
3 types of cardiac valves include
atrioventricular
aortic
pulmonary
dense irregular connective tissue that provides shape and support for the heart
cardiac skeleton
where is the cardiac skeleton found
base of pulmonary trunk, aorta, AV valves
w/in the interventricular and interatrial septa
w/in valve cusps and chordae tendinae
insertion points of atrial and ventricular myocardium
how does the conducting system keep the heart’s beat
generate and conduct waves of depolarization to stimulate myocardial contractions
conducting fibers of the heart
purkinje fibers
3 components of the conducting system
sinoatrial (SA node)
atrioventricular (AV node)
atrioventricular bundle of His (AV bundle)
where is the SA node located
R atrial wall near vena cava
where is the AV node located
R atrial wall near AV valve
where is the AV bundle located
in interventricular septum
SA node is responsible for
atrial contraction
purkinje fibers responsible for
ventricular contraction
modified myocardial fibers
sarcoplasm rich
myofibrils poor
small with few intercalated disks
SA and AV nodes
continuation of AV node
myofibers differentiate into purkinje fibers
glyogen rich cytoplasm
few peripheral myofibers
AV bundle
what stain could be used to distinguish the AV bundle (due to its glycogen rich cytoplasm)
PAS
inflammation of lymphatics
lymphagiectasia
hardening of the arteries
atherosclerosis
necropsy findings for atherosclerosis
thickened aorta and pulmonary arteries
reduced lumen
what stain can be used to observe atherosclerosis
weigert’s resorcin fuchsin
possible causes of atherosclerosis in birds
genetic predisposition
lack of exercise
diet - low antioxidants; marek’s disease affects lipid metabolism
embryonic origin of cardiovascular structures
mesoderm (splanchnic mesoderm)
ectoderm (neural crest cells) - cardiac septa and valves
one of the first functional systems to form in the embryo
cardiovascular system
end of vasculogenesis
endothelial cell differentiation
end of angiogenesis
formation of vessels
order of vasculogenesis
mesodermal cells -> FGF-2 -> hemangioblasts -> VEGF angioblasts -> VEGF ->endothelial cells
angiogenesis is regulated by
PDGF and Tgf-B
endothelial cells’ growth factors induce
differentiation of mesenchymal cells into smooth muscle (tunica media)
from splanchnic mesoderm, the cardiogenic plaque gets pushed backwards by neural tube and starts differentiating into
cardiac tube
endocardial cushions differentiate into ___ to form L and R chambers
septum intermedium
first internal cardiac septum completed
divides R and L ventricles
interventricular septum
division of R and L atria
forms foramen ovale which closes after birth
interatrial septum
function of foramen ovale
so most of the O2 rich blood bypasses the lungs in the fetus
what is the problem if the foramen ovale does not close after birth
unoxygenated blood goes into circulation
vascular arterial valves
aorta
pulmonary artery
L AV valve
bicuspid
R AV valve
tricuspid
valves are formed from
mesenchymal tissue (neural crest cells)
and cavitations of myocardium
cavitations of myocardium made of
papillary muscles
chordae tendinae
the ductus arteriosis should
become a ligament; close
patent ductus arteriosis (PDA)
ductus arteriosis remains open
results of PDA
mixing O2 and non-O2 blood
increased output - heart works harder
murmur
PDA is hereditary in which dog breeds
poodle
collie
german shepherd
persistent right aortic arch
obstructs the lumen of the esophagus
results of persistent right aortic arch
megaesophagus
regurgigation
(valvular or arterial) pulmonary stenosis is more common?
valvular
results of valvular stenosis
R heart failure
syncope
systolic murmur
results of aortic stenosis
L ventricular dilation/hypertrophy
systolic murmur
septal defects include
inter-atrial septal defect
inter-ventricular septal defect
tetralogy of fallot
pulmonary stenosis
enlarged aorta
dilation and hypertrophy of R ventricle
inter-ventricular septal defect
results of tetralogy of fallot
stunted growth and exercise induced cyanosis
blood is about __% cells and about __ liquid
45
55
3 classes of blood cells
erythrocytes
leukocytes
platelets (thrombocytes)
function of RBC
O2, CO2 transport
hematocrit (Ht)
% of RBCs in blood
problem with polycythemia (high Ht)
more viscous blood
could form blood clots
heart has to work harder to pump
biconcave structure of RBC
inc surface area for gas exchange
flexible structure of RBC allows
can go through thin vessels like capillaries
rouleaux
RBCs stacked like coins
most common in horses and cats
histology structure of RBC
filled with Hb
minimal organelles and microtubules to keep shape
crenation
spiky RBCs
most common in pigs
function of platelets
hemostasis - blood clotting
how do platelets clot blood
release fibrinogen granules
fibrinogen turns to fibrin
light and peripheral region of platelet
hyalomere region
-OCS (open canicular system)
-microtubules and actin filaments (rapid degranulation)
dark and central region of platelet
granulomere region
- granules
platelets do not have a nucleus and are fragments of ___
megakaryocytes’ cytoplasm
nucleated cells with small pink granules +/- vacuoles; may not come from megakaryocytes
thrombocytes
thrombocytes’ OCS
surface connected cannicular system
amplifies surface area
inc metabolite exchange
cellular components of the immune system that act mostly outside of the blood/vasculature
WBC
mononuclear cells
lymphocytes
monocytes
PMN cells (granulocytes)
neutrophils (heterophils)
eosinophils
basophils
nucleus shape in granulocytes
lobulated
types of granules
azurophilic - primary
specific - secondary
what cell type are terminally differentiated
leukocytes
neutrophil function
acute inflammation
bacterial infections
pus
most numerous PMN cell in dogs cats and horses
neutrophil
band neutrophils
less mature
not fully segmented nucleus
granules in neutrophils
primary (lysosomes)
secondary - neutral stain, pale pink or blue, sometimes invisible
enzymes in primary granules in neutrophils
myeloperoxidase
lysozyme
defensins
enzymes in secondary granules in neutrophils
collagenases, ones that degrade ECM
bactericidal compounds
secondary granules in heterophils
large acidophilic
eosinophil function
anti-parasitic response
allergy modulation
eosinophilic granules
primary
secondary - acidophilic, major basic protein anti-helminthic
basophil function
allergic response (IgE receptors)
histamine release
basophilic granules
primary
secondary - basophilic, heparin, histamine
mononuclear cell granules
primary azurophilic granules but they don’t stain
no secondary
in tissues, mononuclear cells
replicate
specialize/differentiate
lymphocyte function
cellular and humoral immunity
most numerous mononuclear cell and most numerous leukocyte in herbivores
lymphocyte
lymphocyte granules
generally absent except in granular lymphocytes
primary azurophilic
monocyte (macrophage) function
phagocytosis
immune regulation
monocyte granules
primary azurophilic; usually too small
monocyte cytoplasm contains
vacuoles
leukogram - absolute counts
all WBCs
leukogram - differential counts
each WBC
anticoagulant for mammals
EDTA
anticoagulant for non-mammals
heparin
where is bone marrow found in adults
long bones
sternum
ribs
vertebrae
skull
ilia
components of red marrow in mammals
hematopoietic cords (islands) for hematopoiesis
leaky sinusoidal capillaries
stroma
phagocytic macrophages
yellow marrow
adipose tissue
components of red marrow in birds
hematopoietic cords for myelopoiesis
leaky sinusoidal capillaries
stroma
how do leukocytes move from cords to circulation
active migration
how do erythrocytes move from cords to circulation
pushed by pressure gradient
how do platelets move from cords to circulation
shed from tips of megakaryocytes
stem cell that can give rise to any and all types of blood cells
pluripotent cell
stem cell committed to a specific lineage or series
progenitor cell
committed cell that will mature into a terminally differentiated form
precursor cell
order of erythroid series
proerythroblast
basophilic erythroblast
polychromatophilic erythroblast
orthochromatophilic erythroblast
reticulocyte
erythrocyte
nucleus changes through erythroid series
chromatin condenses
nuclear pyknosis and extrusion
cytoplasm changes through erythroid series
loses ribosomes (basophilic)
loses other organelles
accumulates hemoglobin (eosinophilic)
erythropoietin (EPO) promotes
replication
differentiation
EPO mainly produced in
kidney
order of myeloid granulocyte series (same for neutrophils, eosinophils, basophils)
myeloblast
promyelocyte
(granulocytic) myelocyte
(granulocytic) metamyelocyte
band (granulocyte)
(granulocyte)
nucleus changes through meyloid granulocyte series
chromatin condenses
round - ovoid - band - segmented
cytoplasm changes through myeloid granulocyte series
early on basophilic, later clear
primary azurophilic granules develop
secondary eosinophilic or basophilic granules develop
first identifiable stage of granulocyte
myelocyte
compartments of nuetrophils
granulopoietic compartment (bone marrow)
storage compartment (bone marrow)
circulating pool (blood vessel moving)
marginating pool (blood vessel, wall)
inc in neutrophils in circulating pool
neutrophilia
monocytes leave circulation to become
macrophages
compared to monocytes, macrophages are
larger
inc protein synthesis, golgi and lysosomes
can replicate in tissues
macrophage in liver
kupffer cell
macrophage in CNS
microglial cell
macrophage in skin
langerhans cell
macrophage in LN, spleen
dendritic cell
macrophage in bone
osteoclasts
macrophage in lesions
multinucleated giant cell
where is thrombopoietin produced
liver and kidney
platelet cytoplasm contains
mitochondria
ribosomes
ER
granules
